Chapter 7. System Monitoring

Table of Contents
7.1. System Resources
7.1.1. The top command.
7.1.2. The iostat command.
7.1.3. The ps command
7.1.4. The vmstat command
7.1.5. The lsof command
7.1.6. Finding More Utilities
7.2. Filesystem Usage
7.2.1. The df command
7.2.2. The du command
7.2.3. Quotas
7.3. Monitoring Users
7.3.1. The who command
7.3.2. The ps command -again!
7.3.3. The w command
7.3.4. The skill command
7.3.5. nice and renice

"That's Hall Monitor to you!"Spongebob Squarepants

One of the most important responsibilities a system administrator has, is monitoring their systems. As a system administrator you'll need the ability to find out what is happening on your system at any given time. Whether it's the percentage of system's resources currently used, what commands are being run, or who is logged on. This chapter will cover how to monitor your system, and in some cases, how to resolve problems that may arise.

When a performance issue arises, there are 4 main areas to consider: CPU, Memory, Disk I/O, and Network. The ability to determine where the bottleneck is can save you a lot of time.